Flexible-tread truck



A118- 27, 1929. H. L. MITCHELL 1,725,817

' FLEXIBLE TREAD TRUCK Filed Feb. 25, 1925 4 INVENTOR.

Hacia? M7-MEL# go H 2,/ 7 "Z/W ATTORNEYS.

Patented Aug. 27, 1929.

UNITED STATES PATENT FFICE.

HOLGER L. MITCHELL, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO HARNISCHFEGER CORPORATION, OF MILW'AUKEE, "WISCONSIN, A CORPGRATION OF WTSCONSIN.

FLEXIBLE-TREAD TRUCK.

Application filed February 25, 1.925.

This invention relates to improvements in trucls of the character used in connection with the fiexible treads or endless driving belts of tractors and more particularly to an improved construction of and means for mounting the rollers of the truck whereby they may readily adjust themselves in conformance with the various positions assumedy by the tread members as the tractor moves i0 over an uneven surface.

Tractors of the character referred to comprise, in general, a frame, sprocket wheelsV rotatably supported at each end thereof, an endless flexible belt arranged over the wheels for movement with respect to the frame and for contact. with the ground, and one or more trucks connected to the frame and arranged `between the same and the ground run of the belt, the rollers of the truck or trucks en- 2o gaging the belt to provide a suitable support therefor at points intermediate the sprocket wheels. In tractors as heretofore constructed, however, these trucks have been largely incapable of lateral or transverse adjustment to accommodate lateral tilting of the treads occasioned by unevenness in the ground over which the tractor moves; this in turn greatly impairing the traction while at the same time causing tremendous strain upon the trucks and rollers thereof.

One of the objects of the present invention, therefore, is to provide an improved truck of the character describedvwhich shall be so constructed and mounted that the rollers thereof shall be capable of substantially universal movement with respect to the tractor frame so that when in engagement with the ground run of the driving belt of a tractor said rollers may assume various positions in conformance with the positions assumed by the tread members of the belt as the tractor moves over uneven ground, thus maintaining maximum traction.

Another object is to provide an improved truck of the character described which has many advantages over those heretofore constructed as regards simplicity, durability, cost of manufacture, and iiexibility of operation.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating the invention an embodiment thereof is shown in the drawings, in which Figure l is a side elevation of part of a serial No. 11,411.

tractor showing one form of the improved trucks operatively associated therewith;

Fig. 2 is a section on line 2 2 of Fig. l; Fig. 3 is an .enlarged fragmentary view, showing the manner in which the improved trucks may be connected to the tractor frame for pivotal or rotary movement with respect thereto, and the universal movement of the truck rollers with respect to the tractor frame;

Fig. 4c is an end elevation, looking toward the left in Fig. 3;

Fig. 5 is a bottom plan view of Fig. 3; Fig. 6 is a section on line 6 6l of Fig. 4, the rollers being shown in their normal position when the tractor is on even ground;

Fig. 7 is a section on line 7-7 of Fig. 5; and

Fig. 8 is a side elevation of one of the parts. l Y

Tractors with which trucks made in accordance with the present invention are particularly adapted for use may comprise a frame having a member l at each side thereof, sprocket wheels 2 rotatablymounted at each end of the frame, and an endless flexible belt 3 arranged upon the wheels for relative movement with respect to the tractor frame, suitable means such as idle rollers t being rotatably supported by frame members l and arranged under the upper portion of belt 3 to support and hold the same in proper spaced relation with respect to the frame. Each side memberl l of the frame may be providedwith spaced lugs 5 depending therefrom and provided with registering openings to receive suitable means such as pins G for connecting the improved trucks to the frame for pivotal or'rotary movement about axes transverse to the frame7 the pins being held in vassembled relation by crtter pins 7 passing through the` ends thereo The improved truck and the manner in which the rollers thereof are mounted for universal movement with respect to the tractor frame will now be described, referring more'parti'cularly to Figsl?)y to 8. -'The truck comprises a body portion or bearing member 8 which is provided with openings 9 and l() arranged in different horizontal planes and at right angles with respect to each other to form bearings 11 and 12, respectively, bearing 11 receiving pin 6 whereby the truck is connected to the tractor frame for pivotal or rotary movement about an axis transverse thereto. Bearing 12 receives a suitable shaft 13 upon the ends of which axles 14 and 15 are loosely mounted and .i held in operative position thereon by collars such as collars 2O and cotter pins 21 passing through the collars and the ends 19 of the axles. The body portion 8may be reinforced by meansof va flange 22 connecting bearings 11 and 12. The upper corners of flange 22 may be extended beyond the upper edge thereof to provide stops 23 adapted to engage the under side of framemembers l, as shown in Fig. 3, to limit rotary movement of the truck in either directionv about pin 6. The flanged rollers18 engage the inwardly extending sectional tracks formed by the flanges 24 of the individual tread members 25 shown in Fig. 2, and may rotate about shaft 13 in planes parallel to pin 6 in adjusting themselves to lateral tilting movement of the tread members. If the tractor should meet an obstacle to cause certain of the tread members 25 to tilt about axes transverse to the tractor and assume a position suclras is shown in Fig. 1, the truck will rotate about pin 6 to permit rollers 18 to adjust themselves in accordance with.

such position.

From' the foregoing it will be seen that a truck of the character described has been provided which is simple in construction, durable, one which has great liexibility inoperat-ion and is capable of substantially universal adjustment.

It `will of course be appreciated that shaft 6 may be either lixed against rotation with respect to body portionA 8 or be rotatably mounted therein, as desired.

Various changes in the size, shape and arrangement of theparts may be adopted with- "f`f out departing from the spirit of the inventiont or the scope of the claims.

The invention claimed is:

1. In atractor having aside frame member, a truck provided with sleeve-l`il e bearings arranged in different horizontal planes and at right angles with respect to eachother, one ofthe sleeve-like bearings. beingy adapted to coact with means for positively and directly pivotally connecting the truck to the frame, a shaft mounted in the other sleevelike bearing and projecting beyond the same, axles supported by the shaft for pivotal movement with respect to the truck and rollers mounted on the axles.

2. In a tractor having a side frame member, a truck provided with sleeve-like bearings integrally connected and arranged in different horizontal planes and at right angles with respect to each other, a reinforcing flange integral with and connecting the sleeve-like bearings, one of said sleeve-like bearings being adapted to coact with means for positively and directly pivotally connecting the truck to the frame, a shaft mounted in the other sleeve-like bearing and having its ends projecting beyond the same, axles supported on the projecting ends of the shaft for pivotal movement with respect to the truck and rollers mounted on the axles.

3. In a tractor'having a side frame member formed with a pair of depending spaced pivot lugs, a truck comprising a body portion formed with a transverse bearing adjacent its upper end adapted to be fitted loosely be* tween the lugs of the frame and to be pivotally connected thereto, said body portion also having an integral sleeve-like bearing extending longitudinally thereof and arranged below the transverse bearing, a shaft supported` for the major portion of its extent in the sleeve-like bearing and having its ends projecting beyond the same, axles supported by the ends of the shafts for tilting movement and rollers mounted on the axles.

4. In a truck of the character described, a memberprovided with bearings arranged in different horizontal planes and at right angleswith respect to each other, al reinforcing flangev connecting said bearings, one of said bearings being adapted and arranged to receive means for connecting said member to a tractor frame for rotary movement about an axis transverse thereto, the other of said bearings being adapted and arranged to receive means for connecting rollers to said member for rotary movement in planes parallel to said axis, and stops adapted to engag said tractor fra-me to limit rotary movement of said member in either directionn about said axis.

In witnesswhereof I hereto affix ture.

my signa- I-IIOLGER L. MITCHELL. 

